This invention relates to a distributor for an internal combustion engine having the function of suppressing generation of radio noises therefrom, and more particularly to a distributor of the kind above described having the function of suppressing generation of a radio noise from the distributor portion between the center electrode and the side electrodes thereof.
As is commonly known, radio noises generating in an ignition system of an internal combustion engine have a wide frequency range and provide a source of disturbance which impairs the otherwise comfortable sense of viewing and listening for the television viewers and radio listeners living in a wide area. As a known means put into practice already for the purpose of suppression of generation of radio noises in such an ignition system, ignition plugs each including a resistor are combined with resistance cord type of ignition cables. This prior art combination is appreciated as being an effective means for the suppression of generation of radio noises from the ignition plugs in the ignition system. However, the ignition plugs in the ignition system are not the sole source of radio noises, and the distributor used for distributing the high-voltage pulses sequentially to the ignition plugs is also another non-negligible source of a radio noise.
For the purpose of minimizing the radio noise generated from the distributor in the ignition system, it has been proposed to incorporate a resistor such as a ceramic resistor in the rotor electrode part of the distributor so as to provide a filter effect against the high-frequency noise components. It has also been proposed to provide a discharge gap of 0.06 to 0.250 inches between the rotor electrode and the side electrodes of the distributor. Various other means have been applied to the portions of the rotor electrode and side electrodes participating in the discharge. However, none of the prior art proposals have been successful in attaining the desired effect of noise suppression.
It is therefore a primary object of the present invention to provide a distributor comprising a novel electrode structure so as to minimize generation of the radio noise from the path of high-voltage pulses between the center electrode and the side electrodes of the distributor.
The distributor according to the present invention is featured by the fact that at least one of the rotor electrode and each side electrode has its discharge-participating area finely divided into interspersed conductive regions and high-resistance regions.